1. Field of the Invention
This invention relates generally to containers for cosmetic substances and the like, and more particularly to articles of this type which are intended to provide an air-tight or hermetic seal between a container body and a lid or cover member therefor.
2. Description of the Related Art Including Information Disclosed under 37 CFR Sections 1.97-1.99
The following patents are cited as being of interest in the field to which the present invention pertains.
U.S. Pat. Nos.:
U.S. Pat. No. 3,117,691 PA1 U.S. Pat. No. 3,149,747 PA1 U.S. Pat. No. 5,139,165 PA1 Canadian Patent No. 2,047,926 PA1 British Patent No. 725,882 PA1 British Published Application No. GB 2 100 239A PA1 Japanese Published Application No. 6-144453 PA1 European Published Application No. EP 478 848 A1
U.S. Pat. No. 3,117,691 relates to a container in the form of a vial constituted of HDPE, having on its lip an annular groove (18) with an undercut or shoulder (13). The vial is fitted with a closure cap having an external bead with an undercut shoulder (14), and with a conical lead-in surface (19) on the shoulder so as to facilitate assembly of the cap. Forcible by-pass of the bead and shoulder effects a seating of the edge of the cap into the groove. Sealing is purportedly effected by the engagement of a corner of the bead (14) with a conical surface of the shoulder, as noted in col. 2, line 48 of the patent specification.
U.S. Pat. No. 3,149,747 relates to a retainer construction for releasably joining plastic sheets, utilizing various types of tongue and groove formations, and wherein the respective tongue portions are provided with suitable enlargements or beads so as to enable a snap fit of the tongue portions into the respective groove portions. The use of different plastics is discussed, col. 3, beginning at line 15.
U.S. Pat. No. 5,139,165 involves a container for storage and shipping of photographic film. FIGS. 8(a) and 8(b) illustrate one embodiment wherein a lid (5) is provided with a downwardly facing peripheral groove having an undercut, and is receivable on the lip of a container. The lip in turn, has an enlargement or bead defining a cooperable undercut which can be received in the groove and brought into engagement with the surface of the undercut thereof. The resultant construction is alleged to have sealing characteristics, as noted in col. 3, line 54 of the patent specification.
Still other containers are shown in British Patent No. 725,882 and British Published Application No. GB 2 100 239A.
British Patent No. 725,882 discloses a jar having a lip with an external bead, and a lid having a peripheral groove with an undercut. Assembly of the lid to the jar results in seating of the bead against the undercut surface of the lid groove. British Application No. GB 2 100 239A discloses a container construction utilizing a safety interlock connection effected by cooperable beads on the lid and on the outer wall of a groove of the container lip, the interlock purportedly minimizing the likelihood of the lid being dislodged as a result of internal pressure in the container. Forcible by-pass of the interlocking beads is required during both application and removal of the lid.
Canadian Patent No. 2,047,926 discloses a container/closure construction wherein the lip of the container is provided with an outwardly-facing retainer bead, and the closure lid has a depending skirt with an inwardly facing bead that can by-pass the lip bead when the closure is assembled. An inner depending skirt on the closure is telescopically received in the bore of the neck, to provide a seal of the container interior.
Japanese Published Application No. 6-144453 discloses a method of blow molding a container and simultaneously affixing it to an existing molded closure cap. In accomplishing this, the lip of the container is formed in and occupies a peripheral groove in the closure cap. The latter has various layers of resin incorporated therein, believed to isolate the molded cap from potentially damaging heat transfer that would otherwise occur from the contact of the cap by the molten plastic of the container.
European Published Application No. EP 478 848 A1 relates to a container and closure, wherein the closure and container neck have cooperable bead-and-groove formations which effect a retention of the closure on the container.
One of the problems in the molded plastic container art is that the material must be sufficiently rigid so as to retain the shape and strength of the individual parts, whereby inadvertent distortion of either the container itself or the cap, is minimized. The material must be of sufficient rigidity to avoid being crushed when packaged, and during shipping and storage. At the same time, where it is desired to rely upon a plastic-to-plastic seal between a container lip and a closure cap, some degree of deformation is necessary as a consequence of less than ideal tolerances in the dimensions of the container and cap. Prior efforts to achieve effective seals have, to a large extent, resulted in compromises in the choice of materials, and the particular molded structures utilized for engagement with one another.
In container constructions characterized by relatively large areas of engagement between a lip portion and a closure cap portion, it is generally recognized that gaps tend to develop between the mating surfaces, in spite of the best efforts to avoid them. Stated differently, the absolute contact pressure from one point in a large surface to an adjoining point or to a remote point, is not uniform, in practice. Instead, "high" spots tend to press against each other, and "low" spots tend to become separated from one another. This characteristic is particularly in evidence when sealing a hinged cosmetic compact where cooperating surfaces of the cover and base are held together tightly only at the hinge and clasp; other points of contact are free to gap or bow. It is considered very difficult from a practical standpoint, to reduce this tendency for high and low spots to occur. This is especially true with molded plastic products because of any unpredictable shrinkage which occurs as the plastic cures.
Also, in attempting to provide a rigid container structure, the plastic which is used often lacks the necessary resilience, thereby sacrificing the integrity of any seal that is sought. A rubber gasket is a good example of a resilient article which has the required elastic and memory characteristics to deform and compress as required, when sandwiched between two otherwise rigid components such as a glass jar and a metal lid. Rubber, however, is generally unsuitable as far as possible utilization in the fabrication of containers (compacts, jars) and closures of the type with which the present invention is concerned.